Phylum Annelida segmented worms Annelida ppt 1 Phylum

Phylum Annelida • Segmented round worms • Parapodia – each segment has extentions of

Next Big Advance • Coelom (body cavity) • Body Segmentation • Closed Circulatory system

Copyright ©The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display ANNELIDA Class

Phylum Annelida • ~ 9000 species • Segmentation highly developed – Mesodermal “blocks, ”

Phylum Annelida • Hydrostatic skeleton – – Fluid pressure in coelom provides support &

Function of a hydrostatic skeleton 27 March 2013 Annelida. ppt 8

Phylum Annelida • Setae (“bristles”) of chitin – “anchors” for earthworm – “paddles” for

Phylum Annelida • Closed circulatory system – Multiple “hearts” – Hemoglobin not in blood

Phylum Annelida • Central nervous system – Dorsal brain – Pair of nerves on

Phylum Annelida • Earthworms’ paired nerve cords are fused into single ventral cord •

Phylum Annelida • Class Polychaetes – “many setae, ” clusters with 20+ setae –

Phylum Annelida • Class Earthworms – few setae in 2 -4 clusters per segment

Phylum Annelida • Class Leeches – – pair of bladelike “jaws” posterior “suction cup”

Phylum Annelida • Leeches – Hirudin from leech, Hirudo medicinalis, inhibits blood clotting 27

Annelids Cont’ 27 March 2013 Annelida. ppt 17

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Phylum Annelida “segmented worms” Annelida. ppt 1

Phylum Annelida • Segmented round worms • Parapodia – each segment has extentions of bristles called Setae • Body systems are also segmented (repeating) • Bigger /more complex requires better gas exchange (some w/ gills), and circulation (closed)

Next Big Advance • Coelom (body cavity) • Body Segmentation • Closed Circulatory system • 2 major groups depending on how coelom formed and how the embryo develops – Protostomes – Deuterostomes

Annelida 27 March 2013 Annelida. ppt 4

Copyright ©The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display ANNELIDA Class Polychaeta • Family Amphinomidae • Bearded fireworm (Hermodice carunculata) • White bristles, extended in defense, are venomous Photo Copyright © Diane R. Nelson Setae

Phylum Annelida • ~ 9000 species • Segmentation highly developed – Mesodermal “blocks, ” each with own coelom – Septa between segments 27 March 2013 Annelida. ppt 6

Phylum Annelida • Hydrostatic skeleton – – Fluid pressure in coelom provides support & locomotion Circular muscles Longitudinal muscles Peristaltic locomotion 27 March 2013 Annelida. ppt 7

Function of a hydrostatic skeleton 27 March 2013 Annelida. ppt 8

Phylum Annelida • Setae (“bristles”) of chitin – “anchors” for earthworm – “paddles” for polychaete – Enlarged as jaws in leeches, some polychaetes 27 March 2013 Annelida. ppt 9

Phylum Annelida • Closed circulatory system – Multiple “hearts” – Hemoglobin not in blood cells • reddish-pink color 27 March 2013 Annelida. ppt 10

Phylum Annelida • Central nervous system – Dorsal brain – Pair of nerves on sides of esophagus – Paired ventral nerve cords with paired ganglia in each segment – Transverse nerves connect ganglia in each segment 27 March 2013 Annelida. ppt 11

Phylum Annelida • Earthworms’ paired nerve cords are fused into single ventral cord • Arthropod better illustrates primitive nervous system of both phyla. 27 March 2013 Annelida. ppt 12

Phylum Annelida • Class Polychaetes – “many setae, ” clusters with 20+ setae – parapodia 27 March 2013 Annelida. ppt 13

Phylum Annelida • Class Earthworms – few setae in 2 -4 clusters per segment – Clitellum – stores fertilized eggs until they hatch – Reproduce Sexually – Can regenerate Annelida. ppt 14

Phylum Annelida • Class Leeches – – pair of bladelike “jaws” posterior “suction cup” Predators External parasites, “bloodsuckers” • Secrete anticoagulants • Medicinal use 27 March 2013 Annelida. ppt 15

Phylum Annelida • Leeches – Hirudin from leech, Hirudo medicinalis, inhibits blood clotting 27 March 2013 Annelida. ppt 16

Annelids Cont’ 27 March 2013 Annelida. ppt 17